We have validated a novel method, the "Fluorosome-trans Technique", to measure membrane permeabilities of drugs. The results for 47-marketed drugs show high correlation with human oral absorption. This method employs specific fluorophore-vesicle preparations, and detects fluorescence changes that are proportional to the rate of transfer of compounds through the lipid bilayer. With a suitable plate reader spectrofluorimeter, the method has been adapted to multi-well plates and is being developed for high throughput screening. The method is rapid and inexpensive, requires only micromolar concentrations, employs no animals or living cells, does not require sterile conditions, and uses no radiolabeled materials or expensive detection methods. It is adaptable to robotics and complementary to other tools used in early screening of drug candidates. In phase II we will develop a product that will be predictive of intestinal cell membrane permeability and of the oral absorption of drugs. We will standardize manufacturing and assay conditions for current and new forms of Fluorosomes, increase relevance to intestinal cell membranes, increase compound coverage, and extend the pH range of the Fluorosome assay. We will prepare a Fluorosome for blood-brain barrier permeability applications. High throughput methods for screening compound libraries in multi-well plates, data acquisition procedures, and software modification for data calculation and display will be implemented, the latter via a subcontract with BMG Labtech Inc. A major bottleneck in modern drug discovery is the prediction of which new chemical entities from large libraries possess optimal disposition properties in animals. Good oral absorption is a key property, and the cell culture and artificial lipid models currently used for measuring permeabilities have significant disadvantages, including low throughput. The Fluorosome reagents, buffers and software needed to implement the assays will be sold under license to pharma and biotech users and CROs. The Fluorosome-trans Technique promises to become an efficient, low cost alternative and one which can be applied to the high throughput needs of the pharmaceutical industry. [unreadable] [unreadable]